Spark-plug



W. H. COTTON.

SPARK PLUG.'

APPLICATION FILED MAR. 4, 1919.

1,340,526. Patented May 18,1920.

STE TES WALTER H. COTION, il?! GHICAGG. LLIlIi.

SFARK-PLUG.

Application filed March 4, 1919.

" To all whom t may concern.'

Be it known that I, WALTER H. Co'T'roN, a citizen of the United States of America, and resident of Chicago, county of Cook, and IState of Illinois, have invented certain new and useful Improvements in .Spark-Plugs, of which the following is a specification, and

which are illustrated inthe accompanying drawings, forming a part thereof.

The lnvention relates to spark plugs and especially to those which are known as selfcleaning spark plugs and which are constructed to secure, when used with internal combustion engines, a vigorous sweep of the gases over, the surface upon whichl accumulations of carbon or the like might serve to short circuit the electrodes. The invention contemplates an improved spark plug of the type indicated, and among the objects of the invention is a construction wherein the selfcleaning feature is developed in a form which may be easily and cheaply manufactured and which is effective and durable in use. Other objects of the invention will appear from the following description.

In the accompanying drawings Figure 1 is a side elevation showing one form ofthe improved spark plug,

Fig. 2`is a .central longitudinal sectional view of the same,

Figs. 3 and 4; are bottom and top plan views of the same respectively, and

Fig. 5 is a plan sectional view taken on the line 5-5 of Fig. 2.

In carrying out the invention a metal holder, generally designated 10, is preferably provided. As shown, this holder comprises a socketed body 11 and a tubular threaded stem 12, the bore 13 of the stem being 'of relatively small diameter. The stem 12 may thus be exteriorly formed in different sizes without varying the dimensions of the device in other respects. The grounded electrode, as 14, is mounted upon the outer end of the stem 12 in the usual manner.

vThe insulated electrode 1'5 is mounted in the insulating block 16 to extend centrally through the bore of the stem 12 as usual except that owing to the small size of the bore 13 the annular gap between the electrode 15 and the walls of the stem 12 is relatively short and preferably contains no solid insulating shield. rlhe lower end of Specification of Letters Patent.

Patented May 18, 1920.

Serial No. 280,633.

the insulating'blofk 16 fits within the socketed body 11 of the holder .10 and is firmly secured therein, as by a clamping nut 17.

In this spark plug, the construction affords a chamber, as 18, of substantial size into which a part of the explosive charge of an internal combustion engine (not shown) is compressed. The present invention contemplates the formation of the chamber 18 within the insulating block 16 without requiring the use of a core in the production of the block. For this purpose the insulating block 16 is preferably made of relatively long and narrow cylindrical form and is hollow throughout a substantial part of its length extending from the lower end of the same, the chamber 18 thus produced being, however, as large in diameter at its lowei` end as in any other portion. At its upper end the block 16 is closely fitted about the electrode .15 which is firmly held thereby in any convenient manner, as by the use of a clamping nut 1i?.

A restricted outlet for the chamber 18 is provided by forming the electrode 15 with an enlarged portion 20 which is located within the chamber 18 but adjacent the open end of the same. A narrow annular outlet passage 21 for the chamber 18 is thus provided between the near wall of the block 16 and the exterior of the surface of the enlarged portion 20 of the electrode 15 adjacent the o en end or mouth of the said chamber. oth in entering and leaving the chamber 18 the gases which are compressed therein will sweep rapidly over the surface of the enlarged portion 20 of the electrode 15 and the adjacent surface of the block 16 for keeping these surfaces free from accumulations of any kind. There will also be a rapid movement of the gases through 'the bore 13 of the stem 12 about the corresping part of the electrode 15 and the com sion of a considerable volume of gas witnin the chamber 18 tends to insure that a part of the fresh charge of gas will be brought into the immediate proximitymf the spart gap between the electrodes 14-15.

While the part 20 has been referred to an enlarged portion of the electrode 15 this part need not be formed integral with the electrode and may take the form of a bush ing of insulating material mounted upon the electrode. The use of the enlargement 2O upon the electrode 15 serves to provide a restricted outlet for the chamber 18 without requiring the walls of this chamber to be formed, with any under cutting portions which would necessitate the use of cores or the like in the production of the block 16. Furthermore, as the walls of the chamber 18 are straight throughout the len h of the chamber the block 16 1s of increase strength and is not likely to become broken in use.

I claim as my inventionl. ln a spark plug, in combination, a cylindrical electrode-carrying member of insulating material havin a chamber extending longitudinally withm the same throughout a substantial part of its length and opening at one end of the said member, the other end of the member being closed and the chamber being as large in diameter at its mouth as in any part of the same, and an electrode fixed in the said carrying member and extending through its chamber to and outwardly beyond the mouth of same, a part of the electrode within the chamber but adjacent its mouth bearing an enlargement to provide a restricted annular passage of substantially less cross-sectional area than that of the chamber inwardly beyond' such enlargement, said passage adapted to allow gases to surge into and out of said chamber.

2. In a spark plug, in combination, a cylindrical electrode-carrying member of insulating material having a chamber extending longitudinally within the same throughout a substantial part of its len h and opening at one end of the said mem r, the other end of the member being closed, and an electrode fixed in the said carrying member and extending through its chamber to and'outwardly beyond the mouth of the same, a'

part of the electrode within the chamber but adjacent .its mouth bearing an enlargement to provide a restricted annular passage of substantially less cross-sectional area than that of the chamber inwardly be ond such enlargement, said passage adapte to allow gases to surge into and out of said chamber.

In a spark plug, in combination, a cylindrical electrode-carrying member of insulatng material havin a chamber extend- -ing longitudinally withln the same throughout a substantial part of its lenteh and opening at one end of the said mem r, the other end of the Amember being closed and the Jchamber being as large in diameter at lts vmouth as in any part of the same, an electrode fixed in the said carrying member and I "extending through its chamber to and out- -v j vwardly beyond the mouth of the same, and a 50' upon the electrode within the chamber of bushing of insulating material mounted the curr ing member but adjacent its mouth to provlde a restricted annular passage of .substantially less cross-sectional area than that of the chamber inwardly beyond the said bushing', said passage adapted to allow gases to surge into and out of said chamber.

4. In a spark plug, in combination, a me- Aot gases, and a spark gap between said electrode and holder exterior of Said assage.

5. In a spark plug, in combination, a metallic holder having a socketed body and a tubular stem, a cylindrical electrode-carry-y ing member of insulating material fixed at one end in the socket of the holder and having a chamber extending longitudinally.

within the same throughout a substantial part of the length of the member and open;

ing at the said end of the member in line with the bore of the stem of the holder, the other end of the said insulating member being closed and its said chamber being as large in diameter at its mouth as in any part of the same, an electrode fixed in the closed end of the insulatin member and ex-` tending through its cham r and through the bore of the stem of the holder, a part ofthe electrode within the chamber of the insulating member but adjacent the mouth of lsaid chamber bearing an enlargement to provide a restricted annular passage of substantially less cross-sectional area than that of the said chamber inwardly beyond such enlargement, and a second electrode mounted on the stem of the holder.

6. In a spark plug, in combination, a metallic holder havin a socketed body and a tubular stem, a cy indrical lectrode-carrying member of insulatin material fixed at one end in the socket of t e holder and having a chamber extending longitudinally within the same throughout a substantial part of the length of the member and openmg at the said end of the member substantially in line withthe bore of the stem of the holder, the other end of the said insulating member being closed and its said chamber being as large in diameter at its mouth as in any part of the same, an electrode fixed in the closed end of the insulating member and extending through its chamber and through the bore of the stem of the holder, a bushing of insulating material mounted u n the said electrode within the chamber o the-in sulating member but adjacent the mouth of the chamber to provide a restricted annular passage of substantially less cross-sectional area than that of the said chamber inwardly beyond the said bushing, and a second eleo- 

